68 PROTISTS AND DISEASE 



of the host-cell remaining unchanged. The nucleus of the 

 parasite consists at first of nucleolus, nuclear cavity, and 

 membrane. 



Later the chromatin is arranged in groups of granules, 

 six granules in two rows appear to represent a primitive 

 mitosis. 



A stage with many definite nuclei is followed by sub- 

 division into spores, liberated as bi-flagellate zoospores by 

 rupture of the host-cell. Dangeard also found a series of 

 stages that he was in doubt whether to attribute to Sphaerita 

 or to some other chytridian. No prickle cells (resting 

 sporanges) are described. Being devoid of mycelium 

 Sphaerita belongs to the Myxochytridinae and it differs 

 from Olpidium sufficiently to constitute a separate genus. 

 Chatton and Brodsky found a Sphaerita with the nucleus 

 situated eccentrically, and Dobell found a Sphaerita in 

 Endolimax nana, an amoeba parasitic in the human intestine. 



4. Synchytriaceae. This order of the Chytridiineae is 

 distinguished by the prominence and regularity of sorus- 

 formation in the life-cycle. In some species, e.g. S. taraxaci, 

 this segmentation occurs within the original capsule of the 

 parasite ; in others, e.g. S. succisae, the parasite leaves its 

 capsule, Fig. 19, (7, before subdividing into sporanges. 



Synchytrians are frequent parasites of a great number 

 of flowering plants. Some are limited to one species of 

 host, whilst others have a wider choice : thus S. aureum 

 has been stated to have been found on 180 different host- 



